Evaporative emissions may be caused by fuel vapor escaping from various systems, components, etc., in an engine or other portions of a vehicle. For example, fuel sprayed into an intake manifold, by a fuel injector, may remain on the walls in intake manifold after the engine is shut down and not performing combustion. Consequently, fuel vapor may flow out of the intake system during engine shut down. As a result, evaporative emissions may be increased and in some cases exceed government mandated requirements. Evaporative emissions also have an environmental impact. For example, the emission may create a haze when exposed to sunlight.
Therefore, systems have been developed to capture fuel vapor in intake conduits to reduce evaporative emissions. For example, US 2006/0054142 discloses an intake system with a hydrocarbon trap positioned at a low point in the intake system to capture fuel vapor. Fuel vapors may be absorbed and released from the hydrocarbon trap to reduce evaporative emissions.
However, the Inventors have recognized several drawbacks with the intake system disclosed in US 2006/0054142. For example, the hydrocarbon trap is integrated into a housing of a conduit in the intake system thereby increasing the manufacturing cost of the intake system, as well as reducing the adaptability of the hydrocarbon trap. Moreover, the activated carbon is directly coupled to the housing. The direct attachment of the activated carbon to the housing may inhibit the trap from being easily removed, repaired, and/or replaced, and may increase manufacturing costs. Furthermore, the activated carbon may not properly adhere to the housing. As a result, the activated carbon may be released into the intake system and flow downstream into the engine, degrading engine operation. Additionally, fuel stored in the activated carbon may degrade the housing. Moreover, the hydrocarbon trap is positioned at a low point in the intake system, thereby constraining the position of the hydrocarbon trap.
As such, in one approach an induction system in an engine is provided. The air induction system includes an induction conduit including an air flow passage in fluidic communication with at least one combustion chamber in the engine and a passive-adsorption hydrocarbon trap positioned within the induction conduit, a portion of the passive-adsorption hydrocarbon trap defining a boundary of the air flow passage, the passive-adsorption hydrocarbon trap including a breathable layer coupled to a substrate layer coupled to the induction conduit, a hydrocarbon adsorption layer interposing the breathable layer and the substrate layer.
In this way, the substrate layer may be securely attached to the intake conduit, reducing the likelihood of degradation of the intake conduit via fuel in the adsorption layer and/or degradation of the engine via release of the hydrocarbons. Additionally, when the substrate layer is coupled to the breathable layer to enclose the hydrocarbon adsorption layer, the passive-adsorption hydrocarbon trap may be separately constructed from the induction conduit. As a result, the passive-adsorption hydrocarbon trap may be placed in a greater number of locations when compared to an adsorption layer integrated into an induction conduit. Moreover, the manufacturing costs may be reduced when the hydrocarbon trap is separately constructed from the induction conduit.
In some examples, the breathable layer and an inner wall of the housing of the induction conduit may be contiguous with one another and positioned to form a continuous, uninterrupted linear surface (e.g., without sharp edges, ledges, shelves, or other discontinuities) defining the boundary of the air flow passage, thereby reducing losses in the air flow passage. Further in some examples, the diameter or cross-sectional area of the air flow passage may remain constant transitioning into a section of the induction conduit having the passive-adsorption hydrocarbon trap coupled thereto. As a result, losses in the air flow passages are further reduced, thereby maintaining the efficiency of the induction system.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.